atomic_ops - atomic_*() vs atomic_*_nv()

[raymond.meyer%rambler.ru@localhost]

What's the rationalle for having both:

atomic_*() and atomic_*_nv() functions?

The functions are duplicate of each other, the difference is one does
not return anything and the other returns a new value.

Where would you use either of those functions? If I want to have a
shared counter that doesn't overflow above a certain value, how can
atomic_ops help?